This invention relates to methods of separating sesamin analogues (inclusive of mixtures of sesamin, its stereo isomers and their enantiomers) which are important substances having many physiologically "active" functions such as enhancement of effects of pyrethrin-type insecticides, acceleration of alcohol metabolism, inhibition of generation of peroxidized lipids in blood and inhibition of cancer. This invention relates to methods of efficiently separating such sesamin analogues at a high purity ratio and at a high yield from a steam stripping substance obtained by steam distillation of sesame oil under a reduced pressure condition.
Conventional methods of separating sesamin analogues from a steam stripping substance obtained by steam distillation of sesame oil under a reduced pressure condition includes (1) the method of subjecting the steam stripping substance to a molecular distillation process as disclosed in Japanese Patent Publication Tokko 7-25764 (U.S. Pat. No. 5,209,826); and (2) the method of mixing the steam stripping substance with ethanol, leaving the mixture quietly for a while and thereafter subjecting the supernatant to an adsorption process with resin of methacrylic acid alkyl ester as disclosed in Japanese Patent Publication Tokko 6-89353. The prior art method (1) described above is disadvantageous firstly in that the molecular distillation itself is a troublesome process, secondly in that the steam stripping substance must undergo a pretreatment process in order that the molecular distillation can be carried out efficiently, and thirdly in that the recovery ratio of sesamin analogues is low from the steam stripping substance. By the prior art method (2) described above, on the other hand, the purity of the sesamin analogues recovered by the adsorption process is low and, if it is desired to improve the purity, a refining process must be included and the recovery ratio of the sesamin analogues from the steam stripping substance turns out to be low as a result.